Optical transport network (OTN), developed from synchronous optical network (SONET)/synchronous digital hierarchy (SDH) technology, is a new optical transport technology. It has a relatively good service scheduling capability, networking capability and service protection capability, and is a backbone transport network of the next generation.
With the development of the OTN technology, in order to effectively improve the survivability of services, various types of OTN service protection techniques are provided. Examples of the techniques include optical channel data unit (ODU) shared protection ring (SPRing) suitable for distributed service application scenarios, and ODUk subnetwork connection protection (SNCP) most commonly used by the OTN electrical layer.
In practical applications, several service protections may be configured and used at the same time on a trail of ODUk (where, k may be set to 1, 2, 3, . . . to represent levels, and rates are varied for different levels). Moreover, these kinds of service protection may all need to use an automatic protection switching (APS) protocol. However, in the ODUk frame structure, only four APS/protection communication channel (PCC) overhead bytes can be used for indicating different kinds of service protection. Therefore, how to divide the APS/PCC for multiple service protections becomes a problem to be solved at the present.
In the existing technology, the APS/PCC is divided through multiframes. Particularly, the APS/PCC is divided according to different values of the sixth, seventh, and eighth bits of a multiframe alignment signal (MFAS), so that the APS/PCC is equally divided into 8 parts, and different kinds of connection service monitoring corresponding to the APS/PCC paths after the division and available service protections are set.
However, in actual applications, several ODUk subnetwork connections/non-intrusive monitoring (SNC/N) may perform path monitoring (PM) on the entire ODUk path at the same time, which may result in nesting relations between several service protections, as shown in FIGS. 1 and 2. In this case, according to the standards defined in the prior art, the ODUk SNC/N is assigned with only one APS/PCC value, and is specified with only one service protection path. Therefore, the above-mentioned different ODUk SNC/N service protections may not be distinguished from one another.
In addition, it is not explicitly stated in the prior art the path corresponding to the APS/PCC of which multiframe value that can be used during the ODUk SPRing service protection. If the standards defined in the prior art are used, contention of the paths corresponding to the APS/PCC as shown in FIG. 3 may be caused, and what's worse, nesting relations between several service protections as shown in FIG. 4 may also occur, so that the service protections cannot be easily distinguished from one another.